Markab (AK-31) was built as Mormacpenn by Ingalls 9. B. Co., Pascagoula, Miss.; launched 21 December 1940; acquired by the Navy 2 June 1941 at Charleston, S.C.; and commissioned 15 June 1941, Comdr. Allen D. Brown in command.

Markab operated with Atlantic amphibious forces in the Hampton Roads area until 1 October 1941. She then loaded cargo at Jersey City, N.J., for delivery to American troops recently stationed in Greenland. Returning to Brooklyn, N.Y., 21 November, she took on board supplies for distribution to various bases in the Caribbean. World War II engulfed the United States before Markab steamed into Ensenada Honda, P.R., her first port of call. The new wartime demands on the Navy caused this voyage to terminate at Mobile, Ala., 8 January 1942 where she was converted,to a destroyer tender. Sixteen days later she was redesignated AD-21, but it was 27 September before Commander Brown again commanded a, fully commissioned vessel.

After shakedown Markab transited the Panama Canal 27 October to join Destroyer Force, Pacific Fleet at Pearl Harbor. Ships recently returned from the battle for the Solomon Islands made use of her facilities for 3 months prior to her departure 6 February 1943 to service the North Pacific Force. In the year she remained in the Aleutians, she rendered noteworthy service in helping to prepare vessels for both the Attu and Kiska invasions. Steaming to San Francisco late in January 1944 the ship prepared for an even more extensive Pacific tour.

She departed the west coast 26 February and worked her way toward the war zone. As a part of Service Squadron 10, Markab overhauled, repaired, and replenished destroyers and destroyer escort,, at Pearl Harbor, Majuro, and Eniwetok in the Marshall Islands, and Ulithi in the Carolines. Having assisted in preparing and sustaining the ships fighting in the bloody conquests of the Maranas and Iwo Jima, she sailed for the Philippines 16 February 1945. Her work force now overhauled and readied landing craft for the assualt on Okinawa. During June she played an important part in preparing TF 38 for the last great raids on Japan.

Following Japanese surrender, Markab refitted and restocked ships bound for the occupation areas of Japan, Korea, and China. Steaming in their wake, she arrived Sasebo, Japan, 1 November and early in January 1946 joined the 7th Fleet at Shanghai, China. Her services in the western Pacific ended 2 April as Markab commenced the long voyage home for inactivation. The ship off-loaded at New Orleans beginning 6 May. At Orange, Tex., January 1947, she decommissioned and entered the Atlantic Reserve Fleet.

When the cold war turned hot in Korea, the resultant expansion of the Navy brought the temporary reactivation of Markab. Recommissioned 26 February 1952, Capt. Melvyn H. McCoy in command, she remained on -the east coast servicing Destroyer Force ships. Operating initially at Newport, R.I., and after April 1955 at Fall River, Mass., Markab also participated in the semiannual fleet exercises. On 9 February she departed on a voyage to Charleston where. she decommissioned 31 July.

Into a crisis-beset world she emerged again in 1960. Towed to Mare Island Navy Yard, Calif., she was redesignated AR-23, 15 April and recommissioned 1 July, Capt E. M. Westbrook, Jr., in command. Homeported at Alameda Naval Air Station, the repair ship sailed to Pearl Harbor late in October, returning 22 December. Between 5 July 1962 and 14 September 1966, she projected her services even more widely, steaming three times on 7 month WestPac deployments. On the first such voyage Markab returned a priceless Chinese art treasures exhibit to Taiwan. On the next two tours, ships returning from combat patrol off the coast of Vietnam increasingly required her facilities. Interspersed with the work periods in the Philippines and Japan were brief rest and rehabilitation periods at Hong Kong and Buckner Bay, Okinawa. She has continued this pattern of west coast duty and western Pacific deployment into 1969.